A new model concept has been developed to model the three dimensional energy and mass transfer in an imperfectly mixed fluid. The model permits to predict the dynamic behaviour of the volumetric concentration of heat flow, mass flow and fluid flow. A laboratory test installation has been built to analyse the model capabilities to predict the dynamic behaviour of the air flow pattern within a ventilated space in order to control the energy and mass transfer in the ventilated space.

Preliminary work has indicated that thermography can be used to determine air leakage pathways from or to buildings. Accurate measurements have now been taken using temperature controllable environmental chambers.These results reinforce the potential useof thermography for this application. In conjunction with the physical measurements a simulation has been carried out using computational fluid dynamics.

It has been shown that thermal imaging can give an indication of air flow rates through small cracks. Using a finite difference analysis package it is possible to determine the surface temperature of an air transfer grille when subjected to airflow rates at higher temperatures than the grille surface. This paper will address this technique by presenting the results of the finite difference analysis package for a specific grille.

Multizone models are a common tool for calculating air and contaminant exchange within rooms of a building and between building and outside. Usually a whole room is then modelled by one calculation node with the assumption of homogeneously mixed conditions within this room. In real cases, however, temperature and contaminant concentrations vary in space. The exchange to the neighbouring nodes via the flow paths is then a function of the local values of these variables.

Improvements to ventilation systems for the purpose of saving energy may also affect the provision of good air quality. Measurement of ventilation effectiveness may be used to determine whether or not good fresh air distribution and satisfactory contaminant removal has been achieved in a specific case. However, for such measurements to be useful, it is necessary to establish recommended values of the parameters and to check the reliability of the measurement procedures. This paper is concerned with the second of these problems.

This paper describes a laboratory model for the testing and validation of tracer gas measurement techniques. Previous attempts at experimental validation have often been limited to two zones, or a particular measurement strategy, or a particular range of flows. The model consists of four zones, each of 1m³ internal volume. The zones are connected so that all possible inter-zone flow paths exist. The flow down each path is driven by a pump and monitored by a flow meter. A control panel enables any combination of interzone flows to be set, within the capacity of the pumps.

The equivalent leakage area algorithm is used to illustrate the use of statistical simulations to predict distributions of infiltration and energy loss for buildings. The important parameters in the model are: leakage at 50 Pa pressurisation, indoor and outdoor temperature, leakage in the ceiling and the floor, wind speed, building height and shielding class. Most of these parameters are not known accurately. In the statistical method we assumed for each a distribution based on measurement or good guess.

The traditional description of a flow system with a multicell model, Vc(t)=Qc(t)+p(t), may sometimes be to restrictive. The multicell theory require measurements, or reconstruo tion, of the tracer concentrations in a number of perfect and immediate mixed cells. Often, using of mixing fans and closing doors between cells are necessary to comply with the theory. Another, very usefil and more general description of a flow system is through the weightingfinction. Unlike the multicell model this is not an internal model, but only an input- output model and it is thus less informative.

One of essential problems of the present research related to building analyses is air flows determination. Air flows not only cause energy consumption but also influence air quality parameters, specially in a multizone (and high) buildings. Thepaper presents the main assumptions of the newly developed simulation method. The major departures are addressed which distinguish this alternative method from other multizone models.These include the principles of dividing a dwelling house into zones and the accomplishment of the simulation.

The paper presents a proposal of numerical procedure for air flow simulation in multi-zone buildings (up to 100 zones). This procedure can work with 1 hour time-step according torequirement of TRNSYS-a well-known modular system simulation programme. Co-operation between TRNSYS and my own programme is analysed, taking a typical Polish 5-storey dwelling house as an object of simulation. The proposed numerical procedure can also be run as an independent programme calculating the ventilation air flow, air change rate and heat losses due to infiltration.